clippy_lints/src/methods/filter_map_next.rs

   1 use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg};
   2 use clippy_utils::source::snippet;
   3 use clippy_utils::{is_trait_method, meets_msrv, msrvs};
   4 use rustc_errors::Applicability;
   5 use rustc_hir as hir;
   6 use rustc_lint::LateContext;
   7 use rustc_semver::RustcVersion;
   8 use rustc_span::sym;
   9
  10 use super::FILTER_MAP_NEXT;
  11
  12 pub(super) fn check<'tcx>(
  13     cx: &LateContext<'tcx>,
  14     expr: &'tcx hir::Expr<'_>,
  15     recv: &'tcx hir::Expr<'_>,
  16     arg: &'tcx hir::Expr<'_>,
  17     msrv: Option<&RustcVersion>,
  18 ) {
  19     if is_trait_method(cx, expr, sym::Iterator) {
  20         if !meets_msrv(msrv, &msrvs::ITERATOR_FIND_MAP) {
  21             return;
  22         }
  23
  24         let msg = "called `filter_map(..).next()` on an `Iterator`. This is more succinctly expressed by calling \
  25                    `.find_map(..)` instead";
  26         let filter_snippet = snippet(cx, arg.span, "..");
  27         if filter_snippet.lines().count() <= 1 {
  28             let iter_snippet = snippet(cx, recv.span, "..");
  29             span_lint_and_sugg(
  30                 cx,
  31                 FILTER_MAP_NEXT,
  32                 expr.span,
  33                 msg,
  34                 "try this",
  35                 format!("{}.find_map({})", iter_snippet, filter_snippet),
  36                 Applicability::MachineApplicable,
  37             );
  38         } else {
  39             span_lint(cx, FILTER_MAP_NEXT, expr.span, msg);
  40         }
  41     }
  42 }